"On Mondays directly following the switch to Daylight Saving Time - in which one hour is lost - workers sustain more workplace injuries and injuries of greater severity," the researchers write.

Barnes and Wagner looked at the records of mining injuries between 1983 and 2006, and compared the accident rate on different days before and after a switch to daylight saving.

They say there was a 5.7% increase in the number of injuries on these days and this translated to a 67.6% increase in days of work lost due to the injuries.

In another study, Barnes and Wagner looked at the impact of daylight saving on sleep. They found that between 2003 and 2006, workers reported having on average 40 minutes less sleep on Mondays directly following the switch to daylight saving.

The researchers suggest managers could counteract the impact of daylight saving on accident risk by, for example, adjusting the starting time of employee shifts.

Unjustified

He says a close look at the raw data supplied in the paper shows that there is "absolutely no relationship" between daylight saving and accident rate or amount of sleep.

"My interpretation of their data - from what I can see - is that there actually is no significant relationship between switching on to daylight saving and work accidents [or amount of sleep]," says Roach of the university's Centre for Sleep Research.

But he says it is known from laboratory studies that the less sleep people get the more errors they are likely to make and the more accidents they are likely to have.

Roach says workers who are already getting a restricted mount of sleep should make sure they don't get less when there is a switch to daylight saving.

He says the aim should be to get one hour less awake time rather than one hour less sleep on the 23-hour day that follows a switch to daylight saving.

Results defended

But another Australian psychologist with experience in sleep and circadian rhythms says Barnes and Wagner's "multilevel modelling" is reliable.

Associate Professor Mark Stokes of Deakin University in Melbourne says it is well established that switching to daylight saving causes sleep disturbances.

"It's asking people to go to sleep an hour earlier simply because the clock has changed, but we know people don't do that," he says.

People lie in bed and get annoyed because they can't get to sleep, and this actually prevents them from sleeping well, says Stokes.

"I would think these [Barnes and Wagner's] results are fairly reasonable," he says.